A quote on MSNBC.com given by Gosselin’s lawyer stated:

”[Jon] entered his apartment in Manhattan and was horrified, disheartened, and saddened to observe the devastation of his furniture, clothing and personal belongings, which were apparently slashed with a butcher knife by a very troubled and sick perpetrator,” Gosselin’s lawyer, Mark Jay Heller, said in a statement to Access Hollywood. “Jon immediately contacted me and facilitated the able assistance of the New York City Police Department who immediately dispatched an experienced detective to Jon’s apartment, where a forensic team commenced an intense investigation including photographing and fingerprinting of evidence at the crime scene.

This has to be a very scary event for anyone, especially someone with so many young children.   There are no reports about who actually committed the crime, but hopefully the person is apprehended quickly.